Researchers tested whether a natural fiber called inulin could help people with chronic constipation. Thirty-nine adults took either 12 grams of inulin (a fiber from chicory plants) or a placebo pill every day for four weeks. The people taking inulin had more regular bowel movements, less stomach discomfort, and felt better emotionally about their condition. Scientists also found that inulin changed the types of bacteria in people’s guts in helpful ways. While the results look promising, the study was small and some participants responded better than others, suggesting that inulin might work better for certain people.

The Quick Take

  • What they studied: Does taking a natural fiber supplement called inulin help people who struggle with constipation have more regular bowel movements and feel better?
  • Who participated: 39 adults who had chronic constipation (defined by medical standards) participated in this study. They were randomly assigned to take either inulin or a fake pill that looked identical.
  • Key finding: People who took inulin had noticeably more regular bowel movements and reported feeling better emotionally and socially compared to those taking the placebo. The inulin also increased helpful bacteria in their guts that produce a substance called butyrate, which is good for digestive health.
  • What it means for you: If you have chronic constipation, inulin might be a natural option worth trying before turning to medications. However, it appears to work better for some people than others, depending on what bacteria they already have in their gut. Talk to your doctor before starting any supplement.

The Research Details

This was a randomized, double-blind, placebo-controlled trial, which is considered one of the strongest types of scientific studies. Participants were randomly split into two groups: one received 12 grams of inulin (a natural fiber from chicory root) daily, and the other received a placebo (fake pill) that looked identical. Neither the participants nor the researchers knew who was getting the real supplement or the fake one until the study ended—this “blinding” prevents bias. The study lasted four weeks, and then participants switched groups and did it again for another four weeks.

The researchers measured several things: how often people had bowel movements, how hard or soft their stools were, how much constipation affected their quality of life, and what bacteria lived in their guts. They collected stool samples and used advanced DNA testing to identify which bacteria were present and in what amounts.

This crossover design (where people try both treatments) is useful because it lets researchers compare each person to themselves, which can make results clearer. However, the study found that some people who got inulin first had bigger improvements, which might have affected the results.

Using a placebo control is important because it shows whether inulin actually works or if people just feel better because they think they’re being treated. The double-blind design prevents both patients and doctors from unconsciously favoring one treatment. Testing the actual bacteria in people’s guts using DNA sequencing shows exactly how inulin changes the microbiome, not just whether people feel better.

This study has several strengths: it was published in a peer-reviewed medical journal, it used proper randomization and blinding, and it measured both how people felt and actual biological changes in their gut bacteria. However, the sample size was small (only 39 people), which means results might not apply to everyone. The study also found a “carry-over effect,” meaning people who got inulin first had bigger improvements, which suggests the results might be somewhat biased. The researchers addressed this by analyzing just the first period as a separate study, which still showed benefits.

What the Results Show

People taking inulin had significantly more frequent bowel movements compared to those taking placebo. They also reported less abdominal discomfort and bloating. Most notably, participants reported feeling better emotionally and socially—constipation was bothering them less in their daily lives.

When researchers looked at the gut bacteria, they found that inulin increased the amounts of two types of helpful bacteria: Anaerostipes and Coprococcus. These bacteria produce butyrate, a substance that feeds the cells lining your intestines and helps them work properly. Inulin also increased Bifidobacterium, another type of beneficial bacteria.

Interestingly, the study discovered that some people responded much better to inulin than others. People who started with higher amounts of certain bacteria (Faecalibacterium and Roseburia) and lower amounts of Bifidobacterium showed the biggest improvements. This suggests that your starting gut bacteria might determine how well inulin works for you.

The study found that inulin’s benefits on stool consistency and abdominal symptoms were consistent across most participants. The emotional and social quality-of-life improvements were particularly strong, suggesting that fixing constipation has real mental health benefits. The researchers also noted that the changes in gut bacteria happened relatively quickly—within four weeks—showing that inulin acts fairly fast.

This research supports earlier findings that inulin and similar fibers can help with constipation. The study confirms what scientists already knew about inulin’s “bifidogenic effect”—its ability to increase Bifidobacterium bacteria. However, this study adds new information by showing that inulin also increases other butyrate-producing bacteria and that individual responses vary based on starting gut bacteria composition. The finding that some people respond much better than others is relatively new and important.

The biggest limitation is the small number of participants (39 people), which means results might not apply to everyone. The study only lasted four weeks per treatment, so we don’t know if benefits continue long-term or if people build tolerance. The researchers found a carry-over effect where people who got inulin first had bigger improvements, which could have skewed results. The study didn’t include people with severe constipation or other digestive diseases, so results might not apply to them. Finally, the study didn’t track whether people continued taking inulin after the study ended or how long benefits lasted.

The Bottom Line

If you have chronic constipation, inulin supplementation (12 grams daily) appears to be a safe, natural option that may help improve bowel regularity and quality of life. This recommendation has moderate confidence because the study was well-designed but had a small sample size. Start with your doctor before beginning any supplement, especially if you take medications or have other health conditions. You might notice improvements within 2-4 weeks. However, inulin doesn’t work equally well for everyone—your individual gut bacteria composition may determine how much it helps you.

This research is most relevant for adults with chronic constipation who want to try natural treatments before using medications. It may be especially helpful for people who haven’t responded well to other fiber supplements. However, this study doesn’t apply to people with severe constipation, inflammatory bowel disease, irritable bowel syndrome, or other digestive disorders—they should talk to their doctor about different options. Pregnant women and people with certain food allergies should also consult their doctor first.

Based on this study, you should expect to see improvements in bowel frequency and comfort within 2-4 weeks of starting inulin. However, some people might respond faster or slower. The emotional and quality-of-life benefits appeared alongside the physical improvements. If you don’t notice any changes after 4 weeks, inulin might not work well for your particular gut bacteria, and you should try a different approach.

Want to Apply This Research?

  • Track daily bowel movements (frequency and consistency on a 1-5 scale) and rate your abdominal comfort each evening on a simple 1-10 scale. Also note any changes in how constipation affects your mood or daily activities. This creates a clear picture of whether inulin is working for you personally.
  • Set a daily reminder to take your inulin supplement at the same time each day (ideally with a meal and plenty of water). Log your intake in the app to ensure consistency—the study used 12 grams daily, which is important for results. Gradually increase water intake alongside the inulin, as fiber works better with adequate hydration.
  • Use the app to track your symptoms weekly and create a simple graph showing changes over 4-6 weeks. If you see improvement, continue tracking to make sure benefits last. If you don’t see changes after 4 weeks, note this and discuss alternative options with your doctor. Share your tracked data with your healthcare provider to help them understand what works best for your body.

This research suggests inulin may help with constipation, but it is not a substitute for medical advice. Always consult your doctor or healthcare provider before starting any supplement, especially if you have other digestive conditions, take medications, are pregnant, or have food allergies. Individual results vary, and what works for one person may not work for another. If your constipation is severe or accompanied by other symptoms like blood in stool, unexplained weight loss, or severe pain, seek immediate medical attention. This study was conducted on a small group of people, so results may not apply to everyone.